1. Field of the Invention
The present invention relates generally to controllable hydraulic dampers for vehicular suspensions. In particular, the present invention is concerned with a bypass valve assembly for a hydraulic damper which provides independent control of fluid during compression and rebound strokes of the damper.
2. Description of the Related Art
Variable hydraulic dampers (shock absorbers and struts) are well-known. Many variable dampers include a fluid-filled cylinder divided by a reciprocating piston into first and second fluid chambers. A bypass channel is provided between the chambers and a bypass valve controls fluid flow in the bypass chambers. Oftentimes, a fast-acting solenoid valve is utilized as the bypass valve to provide real time variable damping. When the solenoid valve is energized (opened), fluid is routed through the less restrictive bypass channel, thereby providing a relatively soft damping rate. When the valve is deenergized (closed), fluid does not travel through the bypass channel, thereby providing a relatively firm damping rate as fluid travels through the restrictive piston valving.
The art continues to seek improvements. It is desirable to provide a bypass valve for a variable suspension damper capable of independently controlling fluid flow during compression and rebound strokes of a damper, thereby providing at least four modes of operation. Furthermore, it is desirable to provide an unidirectional bypass valve which can accommodate incoming flow from two sources, such as occurs in a monotube damper.